E85 fuel or %85 denatured alcohol fuel is a less dense fuel when compared to patrol oil fuel or pump gas. This means you need more of it to create the same air to fuel ratio as patrolling gas.
Will it hurt my car?
The short answer to this question is, no. The e85 fuel is a more dry fuel meaning it has less lubricating properties, however it does not hurt your car directly. It actually cleans your engine by burning up carbon deposits and eating away dirty valve deposits left by patrolling fuel.
How do I run e85 safely?
This is achieved by either tricking your ecu to add more fuel with a piggyback engine management system or switching to a standalone engine management system. A piggy back system will allow you to lengthen the pulse width of the injector, adding more fuel to compensate for the fuel density differences (1/3 approximately). A stand-alone engine management system will also do this but while allowing you to change ignition timing. Because the fuel is an alcohol, it is more forgiving when it comes to detonation. We never want the fuel to ignite until we tell it to. We can increase timing which allows for more power production per cylinder without worrying about the spark happening before we tell it to from heat build up in the combustion chamber. Being an alcohol, we do want to make sure any rubber lines are replaced with normal nylon lined fuel hosing to prevent the fuel from eating the rubber.